Drive assist control apparatus and control method for drive assist

ABSTRACT

A drive assist control apparatus assists a driving of a vehicle by controlling a light image projected on a road surface in front of the vehicle. The drive assist control apparatus includes a light image projector, a change portion detector, and a light image corrector. The light image projector projects an informative light image on the road surface. The informative light image represents information to be displayed to an occupant in the vehicle. The change portion detector detects a gradient change portion where a gradient of the road surface changes. The light image corrector corrects a projection position of the informative light image projected by the light image projector. The light image corrector moves the projection position to a position nearer to the occupant than the gradient change portion detected by the change portion detector.

CROSS REFERENCE TO RELATED APPLICATION

This application is based on Japanese Patent Application No. 2015403989filed on May 21, 2015, the disclosure of which is incorporated herein byreference.

TECHNICAL FIELD

The present disclosure relates to a drive assist control apparatus and acontrol method for drive assist.

BACKGROUND ART

Conventionally, a drive assist control technique, which assists drivingof a subject vehicle by controlling a light image projected on a roadsurface of a travelling road in front of the subject vehicle, is knownas a technique for securing safety.

For example, in the drive assist control technique disclosed in PatentLiterature 1, the informative light image, which indicates informationto be displayed to an occupant in the subject vehicle, is projected onthe road surface. As a result, the occupant of the subject vehicle candrive with safety secured based on the information indicated by theinformative light image. A person around the subject vehicle can avoiddanger with safety secured based on the information indicated by theinformative light image.

PRIOR ART LITERATURE Patent Literature

-   Patent Literature 1: JP 2010-95048 A

SUMMARY OF INVENTION

In the drive assist control technique disclosed in Patent Literature 1,a shape or a size of an informative light image is corrected inaccordance with gradient angles of a road surface. With this technique,distortion of the informative light image, which is caused by a gradientof the road surface, can be restricted. Thus, when the informative lightimage is projected to a position farther than a top portion where agradient of the road surface changes, an intended projection position onwhich the light image is projected does not exist on the road surface.So, the information cannot be displayed correctly on the road surface.When the informative light image is projected toward a region fartherthan a sag portion where a gradient of the road surface changes, anactual projection position on which the light image is projectedapproaches nearer than an intended projection position. So, theinformation cannot be displayed correctly on the road surface.

In view of the foregoing difficulties, it is an object of the presentdisclosure to provide a drive assist control apparatus and a controlmethod for drive assist each of which displays information correctly byprojecting a light image on a road surface.

According to an aspect of the present disclosure, a drive assist controlapparatus assists a driving of a vehicle by controlling a light imageprojected on a road surface in front of the vehicle. The drive assistcontrol apparatus includes a light image projector, a change portiondetector, and a light image corrector. The light image projectorprojects an informative light image on the road surface. The informativelight image represents information to be displayed to an occupant in thevehicle. The change portion detector detects a gradient change portionwhere a gradient of the road surface changes. The light image correctorcorrects a projection position of the informative light image projectedby the light image projector. The light image corrector moves theprojection position to a position nearer to the occupant than thegradient change portion detected by the change portion detector.

According to another aspect of the present disclosure, a control methodfor drive assist which assists a driving of a vehicle by controlling alight image projected on a road surface in front of the vehicle isprovided. The control method for drive assist includes projecting aninformative light image on the road surface, in which the informativelight image represents information to be displayed to an occupant in thevehicle; detecting a gradient change portion where a gradient of theroad surface changes; and correcting a projection position of theinformative light image on the road surface to a position nearer to theoccupant than the gradient change portion detected on the road surface.

In the above-described drive assist control apparatus and control methodfor drive assist, when the gradient change portion, which is a part ofthe road surface where the gradient changes, is detected, a projectionposition of the informative light image is corrected to a positionnearer to the user than the gradient change portion. With thisconfiguration, the projection of the informative light image to aposition farther than the gradient change portion can be avoided. So,the information can be displayed correctly on the road surface.

BRIEF DESCRIPTION OF DRAWINGS

The above and other objects, features and advantages of the presentinvention will become more apparent from the following detaileddescription made with reference to the accompanying drawings. In thedrawings:

FIG. 1 is a block diagram showing a vehicle system of a firstembodiment;

FIG. 2 is a schematic diagram showing a projection of a visible lightimage by a projector light in FIG. 1 on a road surface;

FIG. 3 is a schematic diagram showing the projection of the visiblelight image by the projector light in FIG. 1 on the road surface;

FIG. 4 is a schematic diagram showing the projection of the visiblelight image by the projector light in FIG. 1 on the road surface;

FIG. 5 is a schematic diagram showing the projection of the visiblelight image by the projector light in FIG. 1 on the road surface;

FIG. 6 is a graph showing a function of each of blocks configured by anintegrated ECU in FIG. 1;

FIG. 7 is a graph showing the function of each of the blocks configuredby the integrated ECU in FIG. 1;

FIG. 8 is a schematic diagram showing the projection of the visiblelight image on the road surface by the projector light in FIG. 1according to a modification different from FIG. 5;

FIG. 9 is a block diagram showing each of the blocks configured by theintegrated ECU in FIG. 1;

FIG. 10A is a schematic diagram showing the visible light imagegenerated before projection by the projector light in FIG. 1;

FIG. 10B is a schematic diagram showing the visible light imageprojected by the projector light in FIG. 1;

FIG. 11 is a flowchart showing a flow of a drive assist control executedby the integrated EUC in FIG. 1;

FIG. 12 is a schematic diagram showing the projection of the visiblelight image on the road surface by the projector light in a secondembodiment;

FIG. 13 is a block diagram showing each of the blocks configured by theintegrated ECU in the second embodiment;

FIG. 14 is a flowchart showing the flow of the drive assist controlexecuted by the integrated EUC in the second embodiment;

FIG. 15 is a schematic diagram showing the projection of the visiblelight image on the road surface by the projector light in a thirdembodiment;

FIG. 16 is a block diagram showing each of the blocks configured by theintegrated ECU in the third embodiment;

FIG. 17 is a flowchart showing the flow of the drive assist controlexecuted by the integrated EUC in the third embodiment; and

FIG. 18 is a schematic diagram showing the projection of the visiblelight image on the road surface according to a modification differentfrom FIG. 5.

EMBODIMENTS FOR CARRYING OUT INVENTION

Hereinafter, embodiments of the present disclosure will be describedwith reference to the drawings. In each embodiment, sectionscorresponding to items described in the preceding embodiment are denotedby the same reference symbols, and their repetitive description might beomitted. In each embodiment, in the case where only a part of aconfiguration is described, the precedingly described embodiment can beapplied to the other part of the configuration. Except for thecombination explicitly indicated by each embodiment, the configurationsof the embodiments can be partially combined together unless there is acontradiction although no explicit embodiment is described.

First Embodiment

As shown in FIG. 1, a vehicle system 1 to which a first embodiment ofthe present disclosure is applied is mounted on a subject vehicle 2 (seeFIGS. 2 and 3).

The vehicle system 1 includes a peripheral monitor system 3, a vehiclecontrol system 4, and a light image projection system 5. Each of thesystems 3, 4, 5 of the vehicle system 1 is connected to each other viaan in-vehicle network 6, such as LAN (Local Area Network).

The peripheral monitor system 3 includes an outer sensor 30 and aperipheral monitor ECU (Electronic Control Unit) 31. The outer sensor 30may detect a road surface condition, such as a gradient angle, a shape,or a dead angle of a road surface 7. The outer sensor 30 may detect atraffic sign, such as a gradient sign or a traffic indication includinga white line of a lane marking, or the like. The outer sensor 30 maydetect an obstacle which exists outside the subject vehicle 2 and maycollide with the subject vehicle, such as a different vehicle, astructure, a human, or an animal.

The outer sensor 30 may be provided by a sonar, a radar, or a camera.The sonar is provided by an ultrasonic sensor attached to, for example,a front portion or a rear portion of the subject vehicle 2. The sonarreceives a reflected wave of an ultrasonic wave that is emitted to adetection area outside the subject vehicle 2. Based on the receivedreflected ultrasonic wave, the sonar can detect the obstacle, whichexists in the detection area. Then, the sonar outputs a detectionsignal. The radar is provided by a millimeter wave sensor or a lasersensor attached to, for example, a front portion or a rear portion ofthe subject vehicle 2. The radar receives a reflected wave of amillimeter wave, a submillimeter wave, or a laser that is emitted to adetection area outside the subject vehicle 2. Based on the receivedreflected wave, the radar can detect the obstacle, which exists in thedetection area. Then, the radar outputs a detection signal. The camerais provided by a monocular or a compound eye camera, and is attached to,for example, a room mirror or door mirror of the subject vehicle 2. Thecamera takes an image of the detection area outside the subject vehicle2. Based on the image, the camera can detect the obstacle or the trafficsign existing in the detection area. Then, the camera outputs a lightimage signal.

The peripheral monitor ECU 31 is mainly provided by a microcomputerhaving a processor and a memory, and is connected to the outer sensor 30and the in-vehicle network 6. The peripheral monitor ECU 31 may receivetraffic information or obstacle information based on the signal outputfrom the outer sensor 30. The traffic information includes the roadcondition and the traffic sign, and the obstacle information includes arelative position between the subject vehicle 2 and the obstacle.

As shown in FIG. 1 to FIG. 3, a light image projection system 5functioning as a light image projector includes a projector light 50 anda projection control ECU 51. The projector light 50 is provided by lightimage projection type headlights mounted on a right side and a left sideof the front portion of the subject vehicle 2. The projector light 50projects a visible light image 56 on a road surface 7 of a travellingroad in front of the subject vehicle 2 via a projection apparatus mainlyprovided by a crystal liquid panel. The visible light image 56 isgenerated as shown in FIGS. 4 and 5. Specifically, in a vehicle widthdirection (that is, a horizontal direction), at a center of a projectionarea Ap in which the visible light image 56 is projected on the roadsurface 7, the informative light image 56 i is generated. The projectorlight 50 projects the visible light image 56 including the informativelight image 56 i at the vehicle-width center of the projection area Apon the road surface 7.

The informative light image 56 i is projected by the projector light 50so that predetermined information is displayed outside the vehicle to anoccupant in the subject vehicle 2. In the present embodiment, theinformative light image 56 i represents a position of a gradient changeportion 7 s at which the gradient of the road surface 7 is changed asshown in FIGS. 2, 3, 6, and 7. The gradient change portion 7 s includesa top portion 7 st and a sag portion 7 ss. The top portion 7 strepresents a section of the road surface 7 where the gradient graduallychanges from an up direction to a down direction or from a horizontaldirection to the down direction. The sag portion 7 ss represents asection of the road surface 7 where the gradient gradually changes fromthe down direction to the up direction or from the horizontal directionto the up direction.

As shown in FIGS. 4 and 5, the informative light image 56 i is projectedat a position nearer to the occupant than the gradient change portion 7s, such as the top portion 7 st or the sag portion 7 ss. With thisconfiguration, the informative light image 56 i is displayed at aposition nearer to the occupant than a position where the gradientchange portion 7 s actually exists. In the informative light image 56 iof the present embodiment, an existing position of the gradient changeportion 7 s is pointed by a vertex of a triangle. For another example,as shown in FIG. 8, the existing position of the gradient change portion7 s may be indicated by a base edge of an inverted triangle. An outline56 s surrounding the informative light image 56 i of the visible lightimage 56, that is, an outline of projection area Ap has a trapezoidshape that has a long side at a farther position and a short side at anearer position with respect to the occupant.

As shown in FIG. 1, the projection control ECU 51 is mainly provided bythe microcomputer having a processor and a memory. Herein, theprojection control ECU 51 is connected to the projector light 50 and thein-vehicle network 6. The projection control ECU 51 automaticallycontrols the projection operation based on a command output from thevehicle control system 4. In the projection operation, the visible lightimage 56 including the informative light image 56 i is projected by theprojector light 50.

The vehicle control system 4 includes a vehicle sensor 40, an occupantsensor 41, a navigation unit 42, a vehicle control ECU 43, and anintegrated ECU 44. The vehicle sensor 40 is connected to the in-vehiclenetwork 6. The vehicle sensor 40 monitors a drive condition of thesubject vehicle 2. The vehicle sensor 40 may be provided by a speedsensor, an attitude sensor, or a radio wave receiver. The speed sensordetects a speed of the subject vehicle 2, and outputs a speed signalcorresponding to the detected speed. The attitude sensor detects anattitude of the subject vehicle 2 based on an acceleration or the like,and the attitude sensor outputs an attitude signal corresponding to thedetected attitude. The radio wave receiver receives, for example, aradio wave output from a positioning satellite, a radio wave output froma transmitter of a different vehicle performing a vehicle to vehiclecommunication, or a radio wave output from a roadside unit performing aroadside to vehicle communication. The radio wave receiver outputsinformation signal corresponding to the received radio wave. Theinformation signal may include subject vehicle information, whichincludes traveling position and vehicle speed or the like, the trafficinformation, and the obstacle information.

The occupant sensor 41 is connected to the in-vehicle network 6. Theoccupant sensor 41 detects a state of the occupant in the subjectvehicle 2 or an operation made by the occupant. The occupant sensor 41may be provided by a power switch, an occupant state monitor, or anassist switch. The power switch is configured to start an internalcombustion engine or a motor generator of the subject vehicle 2. Thepower switch outputs a power signal in response to a turn-on operationmade by the occupant in the subject vehicle 2. The occupant statemonitor detects an occupant state by capturing an image of the occupantin the subject vehicle 2 using a light image sensor, and outputs a lightimage signal. The assist switch is configured to assist driving bycontrolling the projection of the light image in front of the subjectvehicle 2 on the road surface 7. The assist switch outputs an assistsignal in response to turn-on operation made by the occupant in thesubject vehicle 2.

A navigation unit 42 is connected to the in-vehicle network 6. Thenavigation unit 42 displays navigation information, such as a scheduleddrive route on a display device disposed in the subject vehicle 2. Thenavigation unit 42 displays, on the display device, the navigationinformation, which is stored in an own map database based on acquisitioninformation from the ECU 31 and the output signal from the sensor 40,41.

The vehicle control ECU 43 is mainly provided by the microcomputerhaving the processor and the memory. Herein, the vehicle control ECU 43is connected to the in-vehicle network 6. The vehicle control ECU 43 maybe one of an engine control ECU, a motor control ECU, or a brake controlECU.

The engine control ECU controls the internal combustion engine inresponse to an operation made by the occupant on a gas pedal in thesubject vehicle 2 in order to control the speed of the subject vehicle2. The engine control ECU may also automatically control the speed ofthe subject vehicle 2. The motor control ECU controls the motorgenerator in accordance with an operation made by the occupant on thegas pedal in the subject vehicle 2 in order to control the speed of thesubject vehicle 2. The motor control ECU may also automatically controlthe speed of the subject vehicle 2. The brake control ECU controls abrake actuator in accordance with an operation made by the occupant on abrake pedal in the subject vehicle 2 in order to control the speed ofthe subject vehicle, or the brake control ECU may automatically controlthe speed of the subject vehicle 2.

The integrated ECU 44 is mainly provided by the microcomputer having theprocessor 44 p and the memory 44 m, and is connected to the in-vehiclenetwork 6. The integrated ECU 44 synchronizes other ECUs of the subjectvehicle 2. The integrated ECU 44 controls the projection operation ofthe visible light image 56 which includes the informative light image 56i. Herein, the projection of the visible light image 56 is performed bythe projector light 50. The integrated ECU 44 controls the projectionoperation performed by the projector light 50 through the projectioncontrol ECU 51. The projection may be controlled based on theacquisition information from the ECU 31, the output signal from thesensor 40, 41, and control information in the ECU 43. With the controlof the projection, the integrated ECU 44 cooperates with the light imageprojection system 5 to construct a drive assist control apparatus.Hereinafter, a detail of the drive assist control apparatus will bedescribed.

In the integrated ECU 44, as shown in FIG. 9, multiple blocks 440, 441are functionally constructed by a drive assist control program executedby the processor 44 p. At least a part of the blocks 440, 441 may beconfigured by a hardware including one or multiple ICs or the like.

A change portion detection block 440 corresponding to a change portiondetector detects the top portion 7 st or the sag portion 7 ss as thegradient change portion 7 s. The gradient change portion 7 s may bedetected based on the traffic information acquired by the ECU 31, theattitude represented by the attitude signal output from the attitudesensor, and the traffic information represented by the informationsignal output from the radio wave receiver. The change portion detectionblock 440 outputs a command to the projection control ECU 51 in responseto a detection of the gradient change portion 7 s. As a result, theprojector light 50 starts projection of the visible light image 56,which includes the informative light image 56 i, as shown in FIG. 4.

A light image correction block 441 in FIG. 9 corresponds to a lightimage corrector, and corrects at least the informative light image 56 iof the visible light image 56 projected by the projector light 50. Thelight image correction block 441 includes multiple sub-blocks 442, 443,444, 445, 446.

A start sub-block 442 determines whether to start correcting theinformative light image 56 i or not. In each case where the changeportion detection block 440 detects the top portion 7 st or the sagportion 7 ss as the gradient change portion 7 s, the start sub-block 442determines to start correcting of the informative light image 56 i whenthe projection position Pp (see FIG. 4) arrives at the gradient changeportion 7 s. The start of informative light image correction may bedetermined based on the traffic information acquired by the ECU 31, theattitude represented by the attitude signal output from the attitudesensor, the navigation information stored in the unit 42, the controlinformation from the ECU 43, and the subject vehicle information and thetraffic information represented by the information signal output fromthe radio wave receiver. With this determination, when an arrival of theprojection position Pp to the gradient change portion 7 s is determined,the correction of the informative light image 56 i starts.

A setup sub-block 443 sets a time point executing the correction of theinformative light image 56 i. As shown in FIGS. 6 and 7, the time pointsfor correction include a time point T_(cs) when the correction executedby the start sub-block 442 is started, and multiple time points T_(ca)after the start of the correction. Each of the multiple time pointsT_(ca) is set each time the subject vehicle 2 approaches the gradientchange portion 7 s by a predetermined distance δL. The predetermineddistance δL is defined between the gradient change portion 7 s, which isdetected by the change portion detection block 440, and the position ofthe subject vehicle 2 corresponding to the correction start time pointT_(cs). In the present embodiment, the predetermined distance δL is setto decrease with an increase of the speed of the subject vehicle 2 atthe time point T_(cs). As described above, the predetermined distance 6Lis used for determining each time point T_(ca) after the correction isstarted. The predetermined distance δL may be set based on the speedrepresented by the speed signal from the speed sensor, the controlinformation in the ECU 43, and the subject vehicle informationrepresented by the information signal output from the radio wavereceiver. In an example case shown in FIGS. 6 and 7, when the gradientchange portion 7 s is positioned thirty meters ahead of the subjectvehicle 2, the correction is executed each time the subject vehicle 2approaches the gradient change portion 7 s by five-meters as thepredetermined distance δL.

A correction sub-block 444 shown in FIG. 9 corrects the informativelight image 56 i at each time point T_(cs), T_(ca) set by the setupsub-block 443. This correction is executed to the projection positionP_(p) of the informative light image 56 i. As shown in FIGS. 5 and 8,the projection position P_(p) is moved to a nearer position with respectto the occupant than the gradient change portion 7 s detected by thechange portion detection block 440. In the present embodiment, theprojection position P_(p), is moved to the nearer position with respectto the occupant than the gradient change portion 7 s, that is, thecorrected projection position P_(p) is spaced from the gradient changeportion 7 s by a predetermined distance L_(c) toward the subject vehicle2. The predetermined distance L_(c) may be adjusted corresponding to thespeed of the subject vehicle 2 at the correction start time pointT_(cs). FIG. 10A shows the visible light image 56 that the projectionapparatus of the projector light 50 projects before the visible lightimage 56 is corrected by the correction sub-block 444. FIG. 10B showsthe visible light image 56 that the projection apparatus of theprojector light 50 projects after the visible light image 56 iscorrected by the correction sub-block 444. In the correction, theinformative light image 56 i is moved to the nearer position withrespect to the occupant, that is, the informative light image 56 i ismoved close to a bottom line of the triangle with respect to theoccupant.

With the above-described correction, the correction sub-block 444corrects the shape, the size, and a color of the informative light image56 i. As shown in FIGS. 5 and 8, the shape and the size of theinformative light image 56 i are corrected corresponding to a gradientangle of the road surface 7. In the present embodiment, the attitude andthe position of the subject vehicle 2 are further considered in thecorrection of the shape and the size of the informative light image 56i. The shape and the size of the projection may be corrected based onthe traffic information acquired by the ECU 31, the attitude representedby the attitude signal output from the attitude sensor, the navigationinformation stored in the unit 42, and the subject vehicle informationand the traffic information represented by the information signal outputfrom the radio wave receiver.

The color of the informative light image 56 i is corrected against theprevious color such as green. At the correction start time point T_(cs),the color of the informative light image 56 i changes to another color,such as yellow which more visually stimulates the occupant than thecolor displayed before the correction start time point T_(cs). At thetime point T_(cs) after the correction start time point T_(cs), thecolor of the informative light image 56 i changes to another color, suchas red which more visually stimulates the occupant than the colordisplayed at the correction start time point T_(cs) and the colordisplayed before the correction start time point T_(cs). With thiscorrection, in the present embodiment, a level at which the informativelight image stimulates the occupant increases when the subject vehicle 2approaches toward the gradient change portion 7 s.

The correction sub-block 444 corrects the outline 56 s surrounding theinformative light image 56 i of the visible light image 56 in additionto the informative light image 56 i. The shape and the size of thevisible light image 56, that is, the shape and the size of projectionarea Ap are corrected corresponding to the shape and the size of theinformative light image 56 i. The color of the outline 56 s surroundingthe informative light image 56 i of the visible light image 56 isadjusted to a constant color, such as white in order to show a contrastagainst the informative light image 56 i.

The correction sub-block 444, which corrects the above-described variousprojection states, stores the correction content in a history region 44mr included in the memory 44 m shown in FIG. 1. In the history region 44mr, each time the latest correction content is stored, the old historyis replaced to the latest correction content.

An end sub-block 445 shown in FIG. 9 determines whether to end thecorrection of the informative light image 56 i or not. In a case wherethe gradient change portion 7 s detected by the change portion detectionblock 440 is the top portion 7 st, an end of the correction isdetermined when it is supposed that the subject vehicle 2 arrives at thegradient change portion 7 s. In the present embodiment, when the subjectvehicle 2 travels to a position which enables a projection of theinformative light image at a position farther than the top portion 7 st,the subject vehicle 2 is supposed to arrive at the gradient changeportion 7 s. When the supposition for arrival at the gradient changeportion 7 s is determined, the correction of the informative light image56 i is ended at a time point T_(e) shown in FIG. 6. The supposition forarrival indicates a supposition that the subject vehicle 2 arrives atthe gradient change portion 7 s. In a case where the gradient changeportion 7 s detected by the change portion detection block 440 is thesag portion 7 ss, the end of the correction is determined when thesubject vehicle 2 arrives at the gradient change portion 7 s. With thisdetermination, when an arrival at the gradient change portion 7 s isdetermined, the correction of the informative light image 56 i ends at atime point T_(e) shown in FIG. 7. Each of the determinations may beperformed based on the traffic information acquired by the ECU 31, theattitude represented by the attitude signal output from the attitudesensor, the navigation information stored in the unit 42, and thesubject vehicle information and the traffic information represented bythe information signal output from the radio wave receiver.

A detection determination sub-block 446 shown in FIG. 9 determineswhether the detection of the gradient change portion 7 s planed by thechange portion detection block 440 is normally executed or not during acorrection period CT (see FIGS. 6 and 7). The correction period CT isdefined as a time period from the correction start time point T_(cs)when the start sub-block 442 starts correction to the end time pointT_(e) when the end sub-block 445 ends the correction. During thecorrection period CT while the subject vehicle 2 has not arrived at thegradient change portion 7 s or the subject vehicle 2 is supposed to notyet arrive at the gradient change portion 7 s, the detection of thegradient change portion 7 s must be able to be executed. So, during thecorrection period CT, the detection determination sub-block 446determines whether the gradient change portion 7 s is detected as planedor not. In this determination, when normal detection is determined atthe time point T_(cs), T_(ca), the correction by the correctionsub-block 444 is permitted. When an interruption of the detection isdetermined at the time point T_(cs), T_(ca), the correction is executedbased on the history stored in the history region 44 mr instead of thereal-time correction by the correction sub-block 444. The interruptionof the detection may include the interruption of the acquisition of theinformation that is necessary for the detection of the gradient changeportion 7 s by a disturbance. Since the correction is executed based onthe history data, the same correction can be executed as the correctionperformed before the interruption of the detection to theabove-described projection state, such as the projection position P_(p)of the informative light image 56 i.

With the above-described integrated ECU 44 including the blocks 440,441, a drive assist control flow functioning as a drive assist controlmethod is achieved as shown in FIG. 11. The following will describe thedetail of the drive assist control flow. In the drive assist controlflow of the subject vehicle 2, when the power switch and the assistswitch are turned on, the flow starts. When the power switch or theassist switch is turned off, the flow ends. An “S” in the drive assistcontrol flow indicates each step. The memory 44 m of the integrated ECU44 stores a control program, which achieves the drive assist controlflow. The memory 44 m and memories of different ECUs are configured byone or more storage mediums, such as magnetic mediums or opticalmediums.

In S100, the change portion detection block 440 determines whether thegradient change portion 7 s is detected or not. When the gradient changeportion 7 s is not detected, the flowchart repeatedly executes S100.When the gradient change portion 7 s is detected, the flowchart shiftsto S101. In S101, the change portion detection block 440 outputs acommand to the projection control ECU 51 in order to start projection ofthe visible light image 56 including the informative light image 56 i bythe projector light 50.

In S102, the start sub-block 442 determines whether to start thecorrection of the informative light image 56 i or not. Specifically, inS102, the start sub-block 442 determines whether the projection positionP_(p) of the informative light image 56 i arrives at the gradient changeportion 7 s detected in S100 or not. When the projection position P_(p)of the informative light image 56 i does not arrive at the gradientchange portion 7 s, the flowchart repeatedly executes S102. When theprojection position P_(p) of the informative light image 56 i arrives atthe gradient change portion 7 s, the flowchart shifts to S103.

In S103, the setup sub-block 443 sets the time point T_(cs), T_(ca) atwhich the correction is executed to the informative light image 56 i. InS104, the setup sub-block 443 determines whether the present timearrives at the time point T_(cs) or T_(ca) or not. When the present timedoes not arrive at the time point T_(cs) or T_(ca), the flowchartrepeatedly executes S104. When the present time arrives at the timepoint T_(cs) or T_(ca), the flowchart shifts to S105.

In S105, the correction sub-block 444 corrects the visible light image56 including the informative light image 56 i. In the visible lightimage 56 including the informative light image 56 i, the projectionposition P_(p) is moved to nearer position than the gradient changeportion 7 s with respect to the occupant, and the shape, the size, andthe color of the informative light image 56 i are corrected. For theoutline 56 s surrounding the informative light image 56 i of the visiblelight image 56, the shape and the size are corrected.

In S106 following S105, the correction sub-block 444 stores thecorrection content executed in S105 in the history region 44 mr includedin the memory 44 m. In S107, the detection determination sub-block 446determines whether the detection of the gradient change portion 7 s isnormally executed according to a detection plan in the change portiondetection block 440. When the interruption of the normal detection ofthe gradient change portion 7 s is determined, the flowchart shifts toS108. When the normal detection of the gradient change portion 7 s isdetermined according to the detection plan in the change portiondetection block 440, the flowchart shifts to S110.

In S108 following a determination of the interruption of the normaldetection in S107, the detection determination sub-block 446 reads outthe correction content stored in the history region 44 mr included inthe memory 44 m. In S109, the detection determination sub-block 446corrects the visible light image 56 including the informative lightimage 56 i based on the readout correction content, and then, theflowchart returns to S107.

In S110 following a determination of the interruption of the normaldetection in S107, the end sub-block 445 determines whether to end thecorrection of the informative light image 56 i or not. When the gradientchange portion 7 s detected in S107 is the top portion 7 st, in S110,the end sub-block 445 determines whether the subject vehicle 2 issupposed to arrive at the gradient change portion 7 s or not. When thegradient change portion 7 s detected in S107 is the sag portion 7 ss, inS110, the end sub-block 445 addition to vehicle 2 arrives at thegradient change portion 7 s or not. In each case of the detection of thetop portion 7 st or the sag portion 7 ss, when the end sub-block 445does not determine the supposition for arrival or the arrival, theflowchart returns to S104. In each case of the detection of the topportion 7 st or the sag portion 7 ss, when the end sub-block 445determines the supposition for arrival or the arrival, the flowchartshifts to S111. In S111, the end sub-block 445 sets various projectionstates of the informative light image 56 i, such as the projectionposition P_(p) back to the states before the start of the correction,such as the original position, and then, the flowchart returns to S100.

In the first embodiment, S100 corresponds to a change portion detectionstep, S101 corresponds to a light image projection step, and S102 toS111 correspond to a light image correction step.

Advantages

The following will describe advantages of the first embodiment.

In the first embodiment, when the gradient change portion 7 s of theroad surface where the road surface gradient changes is detected, theprojection position of the informative light image 56 i is correctednearer to the occupant than the gradient change portion 7 s. Thisconfiguration can avoid projecting the informative light image 56 i at aposition farther than the gradient change portion 7 s. Thus, theinformation can be displayed visually and correctly.

In the first embodiment, each time the subject vehicle 2 travels towardthe gradient change portion 7 s by the predetermined distance δL, theprojection position P_(p) of the informative light image 56 i iscorrected. With this configuration, the informative light image 56 i canbe projected on the proper position with consideration of the distancebetween the subject vehicle 2 and the gradient change portion 7 s. Thus,the information can be displayed visually and correctly. In the firstembodiment, the predetermined distance δL is set to be decreased with anincrease of the speed of the subject vehicle 2. Thus, not only thedistance between the subject vehicle 2 and the gradient change portion 7s but also the speed of the subject vehicle 2 is considered in theprojection of the informative light image 56 i at a proper position.Thus, the information can be displayed visually and correctly.

In the first embodiment, when the projection position P_(p) of theinformative light image 56 i arrives at the gradient change portion 7 s,the correction of the projection position P_(p) is started. Thisconfiguration can surely avoid projecting the informative light image 56i farther than the gradient change portion 7 s. Thus, the informationcan be displayed visually and correctly.

In the first embodiment, when the subject vehicle 2 arrives at or issupposed to arrive at the gradient change portion 7 s, the correction ofthe projection position P_(p) of the informative light image 56 i isended. With this configuration, after the projection of the informativelight image 56 i at a position farther than the gradient change portion7 s is avoided, the projection position P_(p) rapidly returns to theoriginally set predetermined place. Thus, the information can bedisplayed visually and correctly.

In the first embodiment, when the detection of the gradient changeportion 7 s, which is planned after the start of the correction, isinterrupted, the same correction carried out before the interruption ofthe detection is executed to the informative light image 56 i. With thisconfiguration, when the planned detection of the gradient change portion7 s is incorrectly interrupted, the correction of the projectionposition P_(p) of the informative light image 56 i can be continued.This correction can avoid projecting the informative light image 56 i ata position farther than the gradient change portion 7 s. Thus, theinformation can be displayed visually and correctly at a higherreliability.

In the first embodiment, along with the correction of the projectionposition P_(p) of the informative light image 56 i to a nearer positionthan the gradient change portion 7 s with respect to the occupant, theshape and the size of the informative light image 56 i are correctedbased on the gradient angles of the road surface 7. This configurationcan avoid projecting the informative light image 56 i at a positionfarther than the gradient change portion 7 s, and can also prevent thedistortion of the informative light image 56 i, which is caused by thegradient of the road surface 7 existing between the vehicle position andthe gradient change portion 7 s. According to the first embodiment, theinformation can be more effectively displayed visually and correctly.

In the first embodiment, the color of the informative light image 56 iis corrected. With this configuration, when the subject vehicle 2approaches the gradient change portion 7 s, more visually stimulativelight image is displayed to the occupant. Thus, the visually stimulativelight image can attract the occupant's attention on the gradient changeportion 7 s where the occupant is likely to make a determinationmistake. Thus, driving safety can be improved. The informative lightimage 56 i, which correctly displays the information with the correctedprojection position can contribute to securing of the driving safety.

Second Embodiment

As shown in FIGS. 12 to 14, the second embodiment of the presentdisclosure is a modification of the first embodiment.

In the informative light image 2056 i according to the second embodimentshown in FIG. 12, a preceding vehicle 8 exists as the obstacle existingin front of the subject vehicle. The preceding vehicle 8 is detected bythe outer sensor 30 outside the subject vehicle 2. The informative lightimage 2056 i is projected at a position nearer to the occupant than thepreceding vehicle 8. Thus, the informative light image 2056 i indicatesthe existence of the preceding vehicle 8 from a position nearer to theoccupant. In the second embodiment, the vertex of the triangle of theinformative light image 2056 i points the existing position of thepreceding vehicle 8. With reference to FIG. 8 in the first embodiment,the existing position of the preceding vehicle 8 may be indicated by abase edge of an inverted triangle. The shape and the size of the outline56 s surrounding the informative light image 2056 i of the visible lightimage 56 are same as the first embodiment.

In the second embodiment, as shown in FIG. 13, the integrated ECU 2044further includes a preceding vehicle detection block 2447. The precedingvehicle detection block 2447 detects the preceding vehicle 8, which isin the followed state. The followed state may be a state in which thedistance between the subject vehicle 2 and the preceding vehicle 8 iswithin, for example, 100 meters. The preceding vehicle 8 may be detectedbased on the obstacle information and the traffic information acquiredby the ECU31, the navigation information stored in the unit 42, thecontrol information in the ECU43, and the subject vehicle information,the obstacle information, and the traffic information represented by theinformation signal output from the radio wave receiver. With thedetection of the preceding vehicle 8, the preceding vehicle detectionblock 2447 outputs a command to the projection control ECU 51 in orderto start the projection of the informative light image 2056 i of thevisible light image 56 by the projector light 50. Corresponding to thisconfiguration, the change portion detection block 440 in the secondembodiment is not equipped with a projection start function.

In the second embodiment, the drive assist control flow executed in thefirst embodiment is executed except for that the informative light image56 i is changed to the informative light image 2056 i.

As shown in FIG. 14, the drive assist control flow in the secondembodiment executes S2112, S2113 before execution of S100. In S2112, thepreceding vehicle detection block 2447 determines whether a precedingvehicle 8 is detected or not. When the preceding vehicle 8 is notdetected, the flowchart repeatedly executes S2112. When the precedingvehicle 8 is detected, the flowchart shifts to S2113. In S2113, thepreceding vehicle detection block 2447 outputs a command to theprojection control ECU 51 to start projection of the visible light image56 including the informative light image 2056 i by the projector light50.

In S100 that follows S2113, when the gradient change portion 7 s is notdetected, detected, the flowchart returns to S2112. When the gradientchange portion 7 s is detected, the flowchart shifts to S102. In thesecond embodiment, the flowchart omits S101 that is executed in thefirst embodiment. After the flowchart executes S111, the flowchartreturns to S2112.

The above-described second embodiment can provide similar advantages asthe first embodiment. In the second embodiment, S2113 corresponds to thelight image projection step.

Third Embodiment

As shown in FIGS. 15 to 17, the third embodiment of the presentdisclosure is a modification of the first embodiment.

The informative light image 3056 i of the third embodiment shown in FIG.15 represents a width of a traffic lane. The traffic lane extends infront direction outside the subject vehicle 2. The informative lightimage 3056 i is projected along a vehicle width direction in a straightmanner from a left edge to a right edge of the traffic lane. Theinformative light image 3056 i represents the width of the traffic lanein the vehicle width direction. The shape and the size of the outline 56s surrounding the informative light image 3056 i of the visible lightimage 56 are same as the first embodiment.

In the third embodiment, as shown in FIG. 16, the integrated ECU 3044further includes a lane detection block 3448. The lane detection block3448 detects the traffic lane that extends in front direction outsidethe subject vehicle 2. The traffic lane may be detected based on theobstacle information and the traffic information acquired by the ECU31,the navigation information stored in the unit 42, and the obstacleinformation and the traffic information represented by the informationsignal output from the radio wave receiver. With the detection of thetraffic lane, the lane detection block 3448 outputs a command to theprojection control ECU 51 in order to start projection of theinformative light image 3056 i of the visible light image 56 by theprojector light 50. Thus, the change portion detection block 440 in thethird embodiment is not equipped with the projection start function.

In the third embodiment, the drive assist control flow in the firstembodiment is executed except for that the informative light image 56 iis changed to the informative light image 3056 i.

As shown in FIG. 17, the drive assist control flow in the thirdembodiment executes S3114, S3115 before execution of S100. In S3114, thelane detection block 3448 determines whether a traffic lane is detectedor not. When the traffic lane is not detected, the flowchart repeatedlyexecutes S3114. When the traffic lane is detected, the flowchart shiftsto S3115. In S3115, the lane detection block 3448 outputs a command tothe projection control ECU 51 to start projection of the visible lightimage 56 including the informative light image 3056 i by the projectorlight 50.

In S100 that follows S3115, when the negative determination is made, theflowchart returns to S3114, and when the positive determination is made,the flowchart shifts to S102. In the third embodiment, the flowchartdoes not execute S101 that is executed in the first embodiment. Afterexecuting S111, the flowchart returns to S3114.

The above-described configuration in the third embodiment can providesimilar advantage as the first embodiment. In the third embodiment,S3115 corresponds to the light image projection step.

Embodiments of the present disclosure have been described above. Thepresent disclosure should not be limited to the above embodiments andmay be implemented in various other embodiments and combinations withoutdeparting from the scope of the present disclosure.

First Modification

According to a first modification, in S105 and the correction sub-block444, the predetermined distance δL may be set to a fixed valueregardless of the speed of the subject vehicle 2. The predetermineddistance δL according to the first modification may also be set by theoccupant. Specifically, the occupant may input the value of thepredetermined distance δL a using the occupant sensor 41 functioning asan input device.

Second Modification

According to a second modification, in S105 and the correction sub-block444, each of the time points T_(ca) may be set each time a presetduration elapses from the correction start time point T_(cs). The presetduration may be set to be decreased with an increase of the vehiclespeed in the second modification. Alternatively, the preset duration inthe second modification may be set to a fixed value regardless of thespeed of the vehicle. The preset duration in the second modification maybe set by the occupant. Specifically, the occupant may input the valueof the preset duration using the occupant sensor 41 functioning as theinput device.

Third Modification

According to a third modification, in S105 and the correction sub-block444, the shape and the size of the informative light image 56 i, 2056 i,3056 i may not be corrected.

Fourth Modification

According to a fourth modification, in S105 and the correction sub-block444, the shape and the size of the outline 56 s surrounding theinformative light image 56 i, 2056 i, 3056 i of the visible light image56 may not be corrected.

Fifth Modification

According to a fifth modification, in S105 and the correction sub-block444, the color of the informative light image 56 i, 2056 i, 3056 i maynot be corrected.

Sixth Modification

According to a sixth modification, in S105 and the correction sub-block444, instead of or in addition to the correction of the color of theinformative light image 56 i, the informative light image 56 i may bedisplayed in a blinking manner, and a frequency of the blinking displaymay be changed with an approach of the vehicle to the gradient changeportion. With this configuration, when the subject vehicle 2 approachesthe gradient change portion 7 s, the display of the informative lightimage 56 i can be performed in more visible and stimulative manner tothe occupant.

Seventh Modification

According to a seventh modification, in S105 and the correctionsub-block 444, as shown in FIG. 18, instead of or in addition to theinformative light image 56 i, 2056 i, 3056 i, the informative lightimage 1056 i, which represents the distance between the subject vehicle2 and the gradient change portion 7 s, may be projected on the roadsurface 7. In the seventh modification, the correction of theinformative light image 1056 i is executed in a similar manner as thecorrection of the informative light image 56 i, 2056 i, 3056 i.

Eighth Modification

According to an eighth modification, in S102 and the start sub-block442, the correction of the informative light image 56 i may be startedbefore the projection position P_(p) arrives at the gradient changeportion 7 s. Specifically, in the eighth modification, when the gradientchange portion 7 s is determined by the change portion detection block440 in S100 prior to the arrival of the projection position at thegradient change portion 7 s, the correction of the informative lightimage 56 i may be started.

Ninth Modification

According to a ninth modification, in S110 and end sub-block 445, beforethe subject vehicle 2 arrives at or is supposed to arrive at thegradient change portion 7 s, the correction of the informative lightimage 56 i may be ended. Specifically, in the ninth modification, thecorrection of the informative light image 56 i may be ended at the timepoint T_(ca) that is prior to the arrival of the subject vehicle at thegradient change portion 7 s.

Tenth Modification

In a tenth modification, the detection determination sub-block 446 maybe omitted, and the correction sub-block 444 may not store thecorrection content. With this configuration of the ninth modification,execution of S106 to S109 may be omitted.

Eleventh Modification

In an eleventh modification, the processors of the multiple ECUsincluding the integrated ECU 44 may achieve the drive assist controlapparatus. Alternatively, the processor of at least one ECU except forthe integrated ECU 44 may achieve the drive assist control apparatus. Inthe eleventh modification, different ECUs except for the integrated ECU44 functioning as the drive assist control apparatus may include theprojection control ECU 51 and the peripheral monitor ECU 31.

Twelfth Modification

In a twelfth modification, the detection of the preceding vehicle 8 maybe replaced with the detection of the gradient change portion 7 s asdescribed in the second embodiment. With this configuration, theprojection position P_(p) of the informative light image 56 i, 2056 i,3056 i may be moved to a nearer position to the occupant than thepreceding vehicle 8.

While the disclosure has been described with reference to preferredembodiments thereof, it is to be understood that the disclosure is notlimited to the preferred embodiments and constructions. The disclosureis intended to cover various modification and equivalent arrangements.In addition, the various combinations and configurations, which arepreferred, other combinations and configurations, including more, lessor only a single element, are also within the spirit and scope of thedisclosure.

1. A drive assist control apparatus assisting a driving of a vehicle bycontrolling a light image projected on a road surface in front of thevehicle, the drive assist control apparatus comprising: a light imageprojector projecting an informative light image on the road surface,wherein the informative light image represents information to bedisplayed to an occupant in the vehicle; a change portion detectordetecting a gradient change portion where a gradient of the road surfacechanges; and a light image corrector correcting a projection position ofthe informative light image projected by the light image projector,wherein the light image corrector moves the projection position to aposition nearer to the occupant than the gradient change portiondetected by the change portion detector.
 2. The drive assist controlapparatus according to claim 1, wherein the light image correctorcorrects the projection position each time the vehicle approaches thegradient change portion by a predetermined distance.
 3. The drive assistcontrol apparatus according to claim 2, wherein the light imagecorrector decreases the predetermined distance with an increase of aspeed of the vehicle.
 4. The drive assist control apparatus according toclaim 1, wherein the light image corrector starts a correction of theprojection position when the projection position arrives at the gradientchange portion.
 5. The drive assist control apparatus according to claim4, wherein the light image corrector ends the correction of theprojection position when the vehicle arrives at the gradient changeportion or the vehicle is supposed to arrive at the gradient changeportion.
 6. The drive assist control apparatus according to claim 4,wherein, after the correction of the projection position starts, when adetection of the gradient change portion to be executed by the changeportion detector is interrupted, the light image corrector corrects theprojection position in a same manner as a previous correction of theprojection position.
 7. The drive assist control apparatus according toclaim 1, wherein, in addition to the correction of the projectionposition, the light image corrector corrects a shape and a size of theinformative light image projected by the light image projectorcorresponding to a gradient angle of the road surface.
 8. The driveassist control apparatus according to claim 1, wherein the light imagecorrector corrects the informative light image projected by the lightimage projector so that the informative light image visually stimulatesthe occupant with an increasing level when the vehicle approaches thegradient change portion.
 9. A control method for drive assist whichassists a driving of a vehicle by controlling a light image projected ona road surface in front of the vehicle, the control method for driveassist comprising: projecting an informative light image on the roadsurface, wherein the informative light image represents information tobe displayed to an occupant in the vehicle; detecting a gradient changeportion where a gradient of the road surface changes; and correcting aprojection position of the informative light image on the road surfaceto a position nearer to the occupant than the gradient change portiondetected on the road surface.